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opencc-zeroDec 2020View details →

Data from: Impacts of habitat on butterfly dispersal in tropical forests, parks and grassland patches embedded in an urban landscape

Dispersal distances of 17 species of butterflies in tropical Singapore were significantly greater in forest than in urban habitat. Butterflies in urban plots frequently moved within suitable habitat (park/grassland) patches but rarely crossed non-habitat patches suggesting potential isolation and a need for urban corridors.

FIGURE 7 in Insights into the Urogymnid whiprays (Chondrichthyes: Batoidea) in the Persian Gulf and the Gulf of Oman, with an amendment of their diagnostic characteristics and dispersal range

FIGURE 7. Maculabatis gerrardi (MM1619, male, DW= 27.2 cm), off Bushehr in the Persian Gulf. scale=10 cm.

FIGURE 5 in Insights into the Urogymnid whiprays (Chondrichthyes: Batoidea) in the Persian Gulf and the Gulf of Oman, with an amendment of their diagnostic characteristics and dispersal range

FIGURE 5. Maculabatis randalli, MM21 (male, DW=37.7 cm), treated as GN6649 by Naylor et al. (2012). Note a fully banded tail.

FIGURE 6 in Insights into the Urogymnid whiprays (Chondrichthyes: Batoidea) in the Persian Gulf and the Gulf of Oman, with an amendment of their diagnostic characteristics and dispersal range

FIGURE 6. Maculabatis arabica, MM602 (female, DW=43.8 cm), included in the mo;ecular analysis by Fernando et al. (2019) under the accession number MK335258. Note to seed-shaped suprascapular denticle without primary denticles and a plain tail.

FIGURE 4 in Insights into the Urogymnid whiprays (Chondrichthyes: Batoidea) in the Persian Gulf and the Gulf of Oman, with an amendment of their diagnostic characteristics and dispersal range

FIGURE 4. Maculabatis randalli, MM40 (female, DW=57.7 cm), treated as GN6668 by Naylor et al. (2012). Note a row of primary denticles followed by 3–4 suprascapular denticles and a fully banded tail.

FIGURE 3 in Insights into the Urogymnid whiprays (Chondrichthyes: Batoidea) in the Persian Gulf and the Gulf of Oman, with an amendment of their diagnostic characteristics and dispersal range

FIGURE 3. Color pattern of the tail (A) incomplete banded tail of a juvenile Maculabatis arabica (MM1582, female, DW =19.2 cm); (B) complete banded tail of a juvenile of M. randalli (MM1583, male, DW=19.2 cm). The molecular data confirmed the distinct identity of both specimens.

FIGURE 2 in Insights into the Urogymnid whiprays (Chondrichthyes: Batoidea) in the Persian Gulf and the Gulf of Oman, with an amendment of their diagnostic characteristics and dispersal range

FIGURE 2. Squamation of the mid-disc, (A) Maculabatis randalli (MM1567, female, DW=32.8 cm), note a 3 heart-shape suprascapular denticle with a row of the primary denticle band; (B) M. arabica (MM1412, male, DW=36.2 cm), note an enlarged seed-shape suprascapular denticle without a primary denticle band.. Head orientated to the left.

FIGURE 1 in Insights into the Urogymnid whiprays (Chondrichthyes: Batoidea) in the Persian Gulf and the Gulf of Oman, with an amendment of their diagnostic characteristics and dispersal range

FIGURE 1. Bayesian inference topology results from the phylogenetic analysis of 1044-bp of the ND2 gene for urogymnid species from the Persian Gulf, the Gulf of Oman and the relevant taxa from GenBank. Bayesian posterior probabilities (PP) are given at nodes. Taxon names are followed by their collection code and/or GenBank accession numbers. Specimens from the Persian Gulf and the Gulf of Oman for which sequence data were generated in the course of this study are in bold.

opencc-zeroJan 2020View details →

The role of spines in anthropogenic seed dispersal on the Galápagos islands

<ol> <li>Dispersal has important ecological and evolutionary consequences for populations, but understanding the role of specific traits in dispersal can be difficult and requires careful experimentation. Moreover, understanding how humans alter dispersal is an important question, especially on oceanic islands where anthropogenic disturbance through species introductions can dramatically alter native ecosystems. </li> <li>In this study, we investigated the functional role of spines in seed dispersal of the plant caltrop (Tribulus cistoidesL., Zygophyllaceae) by anthropogenic agents. We also tested whether anthropogenic or wildlife are more important seed dispersers of T. cistoides on the Galápagos. </li> <li>Tribulus cistoidesis found on tropical mainland and oceanic island habitats. The dispersal structure of T. cistoidesis called a mericarp, and they are typically protected by one pair of upper spines and a second pair of lower spines, but the presence and size of spines varies within and between populations. On the Galápagos, the upper and lower spines protect mericarps from seed predation by Darwin's finches. We tested whether spines play a dual role in dispersal by factorially manipulating the presence/absence of the upper and lower spines to simulate the natural variation in mericarp morphology.</li> <li>The upper spines greatly facilitated seed dispersal, whereas the lower spines had no discernible effect on dispersal. The presence of upper spines increased dispersal rate on shoes by pedestrians 23-fold, on fabrics (e.g. towels) and cars by nearly 2-fold, and the presence of upper spines increased dispersal distance by cars 6-fold. When comparing dispersal rates in habitats with high (roads and foot paths) versus low (arid forest) anthropogenic activity, dispersal rates were demonstrably higher in the habitats with more human activity. </li> <li>These results have important implications for understanding the ecology and evolution of plant dispersal in the Anthropocene. Spines on the fruits of T. cistoidesplay important functional roles in anthropogenic dispersal, whereas native and introduced wildlife play a minor role in dispersal on inhabited islands of the Galápagos. Our results imply that seed predators and humans are jointly shaping the ecology and evolution of contemporary populations of T. cistoideson the Galápagos.</li> </ol>

opencc-by-4.0Dec 2020View details →

Experimental Data for "Seismic wave attenuation and dispersion due to partial fluid saturation: Direct measurements and numerical simulations based on X-Ray CT"

Experimental Data from a Berea sandstone sample. Includes X-ray CT scans and mechanical response of sample. Abstract Quantitatively assessing seismic attenuation caused by fluid pressure diffusion (FPD) in partially saturated rocks is challenging because of its sensitivity to the spatial fluid distribution. To address this challenge we performed depressurisation experiments to induce the exsolution of carbon dioxide from water in a Berea sandstone sample. In a first set of experiments we used medical X-ray computed tomography (CT) to characterise the fluid distribution. At an equilibrium pressure of ~1 MPa and applying a fluid pressure decline rate of ~0.6 MPa per minute, we allowed a change in saturation of less than 1 %. The gas was heterogeneously distributed along the length of the sample, with most of the gas exsolving near the sample outlet. In a second set of experiments, at the same pressure and temperature, following a very similar exsolution protocol, we measured the frequency dependent attenuation and modulus dispersion between 0.1 and 1000 Hz using the forced oscillation method. We observed significant attenuation and dispersion in the extensional and bulk deformation modes, however not in the shear mode. Lastly, we use the fluid distribution derived from the X-ray CT as an input for numerical simulations of FPD to compute the attenuation and modulus dispersion. The numerical solutions are in close agreement with the attenuation and modulus dispersion measured in the laboratory. Our methodology allows for accurately relating attenuation and dispersion to the fluid distribution, which can be applied to improving the seismic monitoring of the subsurface.

Temperature reduces fish dispersal as larvae grow faster to their settlement size

1. As species struggle to cope with rising ocean temperatures, temperate marine assemblages are facing major reorganisation. Many benthic species have a brief but critical period dispersing through the plankton, when they are particularly susceptible to variations in temperature. Impacts of rising temperatures can thus ripple through the population with community-wide consequences. However, responses are highly species-specific, making it difficult to discern assemblage-wide patterns in the life histories of different fish species. 2. Here we evaluate the responses to temperature in the early life histories of several fish species using otolith reconstructive techniques. We also assess the consequences of future warming scenarios to this assemblage. 3. We sampled recent settlers of 9 common species across a temperature gradient in the Mediterranean Sea and obtained environmental data for each individual. Using otolith microstructure we measured early life traits including pelagic larval duration (PLD), growth rate, settlement size, hatching and settlement dates. We used a GLM framework to examine how environmental variables influenced early life history parameters. 4. We show that increasing temperature results in considerable reduction in the dispersal potential of temperate fish. We find a nearly universal, assemblage-wide decline in pelagic larval duration (PLD) of between 10-25%. This was because, with increasing temperature, larvae grew quicker to their settlement size. Settlement size itself was less affected by temperature and appears to be an ontogenetically fixed process. 5. Given current estimates of ocean warming, there could be an assemblage-wide reduction in larval dispersal of up to 50 km across the Mediterranean, reducing connectivity and potentially isolating populations as waters warm. 06-Jan-2021

Data from: Evidence of female preference for odour of distant over local males in a bat with female dispersal

Geographic variation of sexual selected male traits is common in animals. Female choice also varies geographically and several studies found female preference for local males, which is assumed to lead to local adaptation and therefore increases fitness. As females are the non-dispersing sex in most mammalian taxa, this preference for local males might be explained by learning of male characteristics. Studies on preference of females in female-dispersing species are lacking so far. To find out whether such females would also show preferences for local males, we conducted a study on greater sac-winged bats (Saccopteryx bilineata), a species where females disperse and males stay in their natal colony. Male greater sac-winged bats possess a wing pouch that is filled with odoriferous secretion and fanned towards females during courtship display. In a combination of chemical analysis and behavioural preference tests, we analysed whether the composition of wing sac secretion varies between two geographically distinct populations (300 km), and whether females show a preference for local or distant male scent. Using gas-chromatography, we found significant differences in the composition of the wing-sac odours between the two geographic distinct populations. In addition, the behavioural preference experiments revealed that females of both populations preferred scent of geographically distant males over local males. The wing-sac odour might thus be used to guarantee optimal outbreeding when dispersing to a new colony. This is – to our knowledge – the first study on odour preference of females of a species with female-biased dispersal.

Fine-scale genetic structure reflects limited and coordinated dispersal in the colonial monk parakeet, Myiopsitta monachus

The genetic structure of animal populations has considerable behavioural, ecological and evolutionary implications and may arise from various demographic traits. Here, we use observational field data and molecular genetics to determine the genetic structure of an invasive population of monk parakeets, Myiopsitta monachus, at a range of spatial scales, and investigate the demographic processes that generate the observed structure. Monk parakeets construct large nests that can house several pairs occupying separate chambers; these nests are often aggregated within nesting trees. We determined patterns of relatedness within compound nests, within nesting trees and between trees. Spatial autocorrelation analyses of pairwise genetic relatedness revealed fine-scale genetic structure with relatives of both sexes spatially clustered within, but not beyond, nesting trees. In addition, males were more related to males sharing their compound nests than to other males occupying the same nesting tree. By contrast, males and females within compound nests were not significantly more closely related than elsewhere in the same tree, and we found no evidence for inbreeding. Adults showed high breeding site fidelity between years despite considerable disturbance of nest sites. Natal dispersal was female-biased, but dispersal distances were relatively short with some natal philopatry observed in both sexes. Sibling coalitions, typically of males, were observed amongst both philopatric and dispersing birds. Our results show significant clustering of kin within compound nests and nesting trees resulting from limited and coordinated natal dispersal, with subsequent breeding site fidelity. The resulting genetic structure has implications for social behaviour in this unusual parrot species.

Data from: Combining climate, land use change and dispersal to predict the distribution of endangered species with limited vagility

Aim: Many rare species are dispersal-limited and minimal land use and climate changes can impact their colonization capacity. Most ecological niche models predict the distribution of species under future climate and land use change scenarios without incorporating specie-specific dispersal abilities. Here we investigated the effect of climate and land use change on low vagile species accounting for their dispersal capacity and defined accessible areas in the future. Location: Europe. Taxon: Saproxylic beetles. Methods: We used the current (2007-2012) occurrences of six endangered saproxylics to develop ecological niche models using current climate and land use conditions. We projected species distributions under four future climate and land use change scenarios to estimate their potential occurrences. Finally, accounting for species-specific dispersal, we limited their distributions to accessible areas in 2040-50. Results: Without accounting for dispersal abilities we found a strong and positive impact of climate change on the distribution of Cerambix cerdo, Cucujus cinnaberinus, Morimus funereus and Rosalia alpina and a positive effect of land use change on the distribution of Lucanus cervus and Osmoderma eremita. When species-specific dispersal was included, we found a strong and positive impact of land use change on the distribution of all the species. In this case climate change had a lower but positive effect on the distribution of C. cerdo, C. cinnaberinus, L. cervus and R. alpina, and a negative effect on the distribution of O. eremita. Main conclusion: We found that climate change would promote the expansion of saproxylic beetles only in the unrealistic case of unlimited dispersal. Accounting for dispersal abilities, the expansion of our species would be mainly conditioned by the effect of land use change. Thus, we encourage researchers to combine climate and land use change with dispersal when projecting species distribution under future scenarios to accurately identify areas with fundamental species-specific resources.

Changes in tree community structures in defaunated forests are not driven only by dispersal limitation

1. Bushmeat hunting has reduced population sizes of large frugivorous vertebrates throughout the tropics, thereby reducing the dispersal of seeds. This is believed to affect tree population dynamics, and therefore community composition, because the seed dispersal of large-seeded trees depends upon large-bodied vertebrates. 2. We report on a long-running study of the effect of defaunation on a tropical tree community. In three censuses over 11 years, we compared sapling recruitment between a hunted and a nonhunted site, which are nearby and comparable to one another, to determine the extent to which species composition has changed through time following defaunation. We expected to find a reduced abundance of tree species that rely on large frugivores for dispersal at the hunted site, and altered community structure as a consequence. 3. Although community composition at the hunted site diverged from that at the nonhunted site, the changes were independent of dispersal syndrome, with no trend towards a decline in species that are dispersed by large, hunted vertebrates. Moreover, the loss of large-bodied dispersers did not generate the changes in tree community composition that we hypothesised. Some species presumed to rely on large-bodied frugivores for dispersal are effectively recruiting despite the absence of their dispersers. 4. Synthesis: The presumption that forests depleted of large-bodied dispersers will experience rapid, directional compositional change is not fully supported by our results. Altered species composition in the sapling layer at the hunted site, however, indicates that defaunation may be connected with changes to the tree community, but that the nature of these changes are not unidirectional as previously assumed. It remains difficult to predict how defaunation will affect tree community composition without a deeper understanding of the driving mechanisms at play.

opencc-zeroNov 2019View details →

Genomic footprints of a biological invasion: introduction from Asia and dispersal in Europe of the topmouth gudgeon (Pseudorasbora parva)

Facilitated by the intensification of global trading, the introduction and dispersal of species to areas in which they are historically non-native is nowadays common. From an evolutionary standpoint, invasions are paradoxical: not only non-native environments could be different from native ones for which introduced individuals would be ill-adapted, but also small founding population size should be associated with reduced adaptive potential. As such, biological invasions are considered valuable real-time evolutionary experiments. Here, we investigated the population structure and adaptive potential of the highly invasive topmouth gudgeon (Pseudorasbora parva) across Europe and East Asia. We RAD-sequenced 301 specimens from sixteen populations and three distinct within-catchment invaded regions as well as two locations in the native range. With 13785 single nucleotide polymorphisms, we provide conclusive evidence for a genome-wide signature of two distinct invasion events, in Slovakia and Turkey, each originating from a specific area in the native range. A third invaded area, in France, appears to be the result of dispersal within the invasive range. Few loci showed signs of selection, the vast majority of which being identified in the Slovakian region. Functional annotation suggests that faster early stage development, resistance to pollution and immunocompetence contribute to the invasion success of the local habitats. <a name="_Hlk15399671">By showing that populations in the invasive range have different evolutionary histories, our study reinforces the idea that populations, rather than species, are the units to consider in invasion biology. </a>

opencc-zeroDec 2016View details →

Data from: Dispersal barriers and climate determine the geographic distribution of the helicopter damselfly Mecistogaster modesta

Species' ranges are typically constrained by the interplay of physical barriers to dispersal, environmental requirements such as suitable climatic conditions and biotic constraints such as from predation or competition. However, teasing apart the relative importance of these constraints in determining species distributions still represents a major challenge for ecologists. The Neotropical damselfly Mecistogaster modesta (Coenagrionidae: Odonata) inhabits wet and moist forests in mainland Central America and north-western South America. This habitat specialist spends its larval development exclusively in tank bromeliads, where it acts as a keystone predator within the aquatic food web. Although tank-forming bromeliads occur from the southern United States throughout most of South America, M. modesta is absent from the Caribbean islands and South America south-east of the Andes mountain chain. We employed species distribution models to explore the relative importance of physical barriers (Andes mountain range and oceanic barriers), climate (mean annual temperature and annual precipitation) and biotic interactions (competition from other bromeliad-dwelling odonates) in limiting the geographic distribution of M. modesta. We found that dispersal barriers strongly limit the geographic distribution of M. modesta. In addition, its range is restricted by low temperatures and low precipitation. Competition from other bromeliad-dwelling odonates was not important in limiting the damselfly's range. Because of the physical barriers to dispersal, M. modesta does not occupy its full potential geographic range. Specifically, our model predicted suitable habitat on the Caribbean islands and throughout most of South America, where the species is currently absent. These findings have important conservation implications, particularly as the aridification of rainforests and subsequent localised extinctions due to climate change continue. On the other hand, the species may respond to warming temperatures by tracking climate to higher elevations, with subsequent effects on naïve high-elevation bromeliad food webs. An upwards migration could also increase the probability of M. modesta overcoming the dispersal barrier presented by the Andes, enabling the damselfly to invade large areas of suitable habitat in South America.

opencc-zeroDec 2014View details →

Data from: Estimating the molecular evolutionary rates of mitochondrial genes referring to Quaternary Ice Age events with inferred population expansions and dispersals in Japanese Apodemus

Background: Determining reliable evolutionary rates of molecular markers is essential in illustrating historical episodes with phylogenetic inferences. Although emerging evidence has suggested a high evolutionary rate for intraspecific genetic variation, it is unclear how long such high evolutionary rates persist because a recent calibration point is rarely available. Other than using fossil evidence, it is possible to estimate evolutionary rates by relying on the well-established temporal framework of the Quaternary glacial cycles that would likely have promoted both rapid expansion events and interisland dispersal events. Results: We examined mitochondrial cytochrome b (Cytb) and control region (CR) gene sequences in two Japanese wood mouse species, Apodemus argenteus and A. speciosus, of temperate origin and found signs of rapid expansion in the population from Hokkaido, the northern island of Japan. Assuming that global warming after the last glacial period 7–10 thousand years before present (kyr BP) was associated with the expansion, the evolutionary rates (sites per million years, myr) of Cytb and CR were estimated as 11–16% and 22–32%, respectively, for A. argenteus, and 12–17% and 17–24%, respectively, for A. speciosus. Additionally, the significant signature of rapid expansion detected in the mtDNA sequences of A. speciosus from the remaining southern main islands, Honshu, Shikoku, and Kyushu, provided an estimated Cytb evolutionary rate of 3.1%/site/myr under the assumption of a postglacial population expansion event long ago, most probably at 130 kyr BP. Bayesian analyses using the higher evolutionary rate of 11–17%/site/myr for Cytb supported the recent demographic or divergence events associated with the Last Glacial Maximum. However, the slower evolutionary rate of 3.1%/site/myr would be reasonable for several divergence events that were associated with glacial periods older than 130 kyr BP. Conclusions: The faster and slower evolutionary rates of Cytb can account for divergences associated with the last and earlier glacial maxima, respectively, in the phylogenetic inference of murine rodents. The elevated evolutionary rate seemed to decline within 100,000 years.

opencc-zeroDec 2017View details →

Data from: Geographic isolation and larval dispersal shape seascape genetic patterns differently according to spatial scale

Genetic variation, as a basis of evolutionary change, allows species to adapt and persist in different climates and environments. Yet, a comprehensive assessment of the drivers of genetic variation at different spatial scales is still missing in marine ecosystems. Here, we investigated the influence of environment, geographic isolation, and larval dispersal on the variation in allele frequencies, using an extensive spatial sampling (47 locations) of the striped red mullet (Mullus surmuletus) in the Mediterranean Sea. Univariate multiple regressions were used to test the influence of environment (salinity and temperature), geographic isolation, and larval dispersal on Single Nucleotide Polymorphisms (SNPs) allele frequencies. We used Moran's Eigenvector Maps (db-MEMs) and Asymmetric Eigenvector Maps (AEMs) to decompose geographic and dispersal distances in predictors representing different spatial scales. We found that salinity and temperature had only a weak effect on the variation in allele frequencies. Our results revealed the predominance of geographic isolation to explain variation in allele frequencies at large spatial scale (> 1,000km) while larval dispersal was the major predictor at smaller spatial scale (< 1,000km). Our findings stress the importance of including spatial scales to understand the drivers of spatial genetic variation. We suggest that larval dispersal allows to maintain gene flows at small to intermediate scale, while at broad scale, genetic variation may be mostly shaped by adult mobility, demographic history or multi-generational stepping stone dispersal. These findings bring out important spatial scale considerations to account for in the design of a protected areas network that would efficiently enhance protection and persistence capacity of marine species.